Media release: Electric Vehicle batteries lasting well so far

Nissan Leaf batteries will deliver at least 85 km range on average after 10 years, with some models going further. This estimate is from Flip the Fleet, a citizen science coalition of electric and plug-in hybrid vehicle owners that upload data from their vehicles to a communal database each month.

“Many people are understandably passionate about battery health in their electric vehicles”, says Dr Myall, Flip the Fleet’s statistician. “It determines the EV’s range and affects resale value. Just as your cellphone battery gradually loses its ability to hold charge, so too an EV cannot store as much energy as it gets older”.

“For most EV owners, we have good news”, says Dr Myall. “The battery in Nissan Leafs, one of the commonest EVs on our roads, loses on average between 2% and 4% of its range each year”.

“In an earlier questionnaire, most EV owners reported that, ideally, they will want to refurbish their battery or replace their EV once its range falls to around 85 km. The actual average daily travel by car in New Zealand is less than 29 km. We expect Nissan Leafs to achieve at least this distance for many years to come”, says Dr Myall.

The Flip the Fleet team are struck by the huge variation between cars in battery health – one has only slipped to 95% charge holding capacity over 5 years, while another is down to 71% after 6 years. The citizen science project wants to find out why some batteries last way longer than others so they can advise how owners can protect their investment. It is the age of the car that matters most – there is no evidence in the Flip the Fleet database so far that battery capacity is greatly affected by overall distance travelled or how many fast charges it has had.

“We need more data for EVs as they age in New Zealand conditions before we can find out what causes the variation in battery health, and to check that rates of decline observed so far continue throughout the life of the battery. We hope more EV owners will sign-up to help Flip the Fleet so that we can learn faster”, says Dr Myall.

Considering that the first Nissan Leafs hit the road in 2011, some will become impractical by 2021 – which is another 4 years away. The most pessimistic outcome would have the earliest EVs needing battery refurbishment in a few years. Batteries in the newer and more expensive electric vehicles are expected to have a longer life than these early Leaf models.

Fortunately, New Zealand already has a fledgling battery refurbishment industry, led by Carl Barlev from Bluecars in Auckland.

“We just need to scale up this support industry in the next few years to extend the life of these very early entry-level EVs”, says Mr Barlev.

“The battery can have an afterlife as a power storage pack in your house. But propelling your car for over ten years is a good first innings and well within the range where the savings on the fuel and maintenance more than pays for the replacement battery you will need eventually. At the moment, refurbishing your battery will cost between $2,000 and $5,000, not much for at least another decade of low cost motoring”, says Mr Barlev.

The newer model EVs have bigger and better batteries, so it’s even less of an issue for them. All up then, battery capacity decline is likely to be a small and manageable issue for most EV owners and battery replacement costs are sufficiently low to make electric vehicles an excellent life time value proposition.

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More information:

The Flip the Fleet project is described at: www.flipthefleet.org. See the ‘Discussion’ and the ‘Resources’ pages there for further data and results of a recent survey of New Zealand’s electric vehicle owners about battery health.

Flip the Fleet has members spread throughout New Zealand. We list the contact details of some local contributors below in case you want to get a local perspective for your story. Please ring 027 2268688 or Email wecan@flipthefleet.org so we can find a local member to speak to you.

Comments

I wonder if you have enough data to support the statement that “The battery will last longer if it is only charged to 80% of its capacity every time it is charged.”
We have chosen this action for our Leaf, and the decline in battery health appears to have halted, and even seems to be improving.
Regards,
Albie Burgers.

Hi Albie, you ask a very good question! That is indeed a very common statement and belief. I’ll check with Henrik to see if we have any data to back this up, and will write about it if we do – for now, I don’t think so, but we’ll look into it for you 🙂 Cheers, Dima.

I have looked at this is the data and so far there is no indication of a difference in decay of battery health between people who said they primarily charge to 80% versus others who charge to 100%. However, there is reasonable uncertainty in the estimated effect, so more data is required to provide a definite answer. It is also likely to be dependent on temperature and time left at 100% charge.

I suspect that characteristic performance may vary between older and newer types of battery. We were charging our 2016 30kWh LEAF TEKNA to 80% (approx using timed charges) for several months, but have recently switched to charging to 100% (at night using specified end time of 7am) and our battery appears to be offering more consistently higher SoH and Hx values than before. We do use the car every day, so it is never left at 100% indicated for more than a few hours before at least a few % are skimmed off. We are currently averaging about 50kM/day. Hopefully the survey will yield some clearer results on all this now that Hx data is now being captured as well as SoH. From our observations, SoH correlates positively with positive changes in Hx.